1. Field of the Invention
The present invention relates to a method for position determination in a position measuring device, as well as to a position measuring device for executing the method.
2. Description of the Related Art
Position measuring devices are increasingly required to meet the requirements of highly dynamic drive mechanism regulations. Also, direct drive mechanisms, with which a high regulating quality can be achieved, are increasingly being employed. A requirement for this is an accurate and dynamic position and velocity determination. At present, the position determination is preponderantly based on incremental or absolute angle encoders or linear measurement encoders. Position information is generated in interpolation circuits by the amplitude information contained in the sinusoidal scanning signals, which has a many times higher resolution than the graduation period of the position measuring device. As a rule, the velocity is determined by time-discrete differentiation of the position, and the acceleration by further differentiation of the velocity.
An article by D. Mann, entitled “Verbesserte Auswertung von inkrementalen Gebersystemen durch Oversampling” [Improved Evaluation of Incremental Encoder Systems by Oversampling], is found in the source materials of the seminar on position regulation “Fortschritte in der Regelungs- und Antriebstechnik” [Advances in Regulating and Drive Technology] of Nov. 13 and 14, 1998. In this article it is stated that the position determination, as well as the velocity determination, can by improved by oversampling. In this case, oversampling is defined by adding up all position values in the course of a scanning step of the regulator (sequential electronic device), and subsequent division by their number. From FIG. 11 and FIG. 15 it can be determined that the position measuring device itself only provides the analog scanning signals A and B, and further processing, including the oversampling process, takes place in the sequential electronic device. However, the transmission of analog position measuring values is relatively susceptible to interference and noise, and the high number of lines between the position measuring device and the sequential electronic device is also negative.